Implantable compression screws

Abstract

A compression screw for applying compression at a bone joint. The compression screw includes an axial screw body extending from a distal end to a proximal end with the distal end including a series of bone engaging threads configured to be self-drilling and self-tapping and the proximal end including a head which defines a radially extending shoulder. At least one proximal rotary cutting structure is defined proximally of the bone engaging threads. The at least one proximal rotary cutting structure is configured to be self-drilling such that a proximal portion of the axial screw body cuts into and advances within a bone of the bone joint as the axial screw body is advanced. A method of inserting the compression screw is also provided.

What is claimed is: 
     
       1. A method for applying compression between a first bone portion and a second bone portion having a gap therebetween, the method comprising:
 providing a compression screw having an outer sleeve and an inner bone screw, the outer sleeve having a non-threaded head which defines a radially extending shoulder, the inner bone screw having a proximal threaded portion being threadedly engaged with the outer sleeve, wherein a distal end of the proximal threaded portion has at least one cutting flute configured to cut into the first bone portion as the inner bone screw is rotated, and wherein the inner bone screw includes a distal threaded portion and a non-threaded portion between the distal threaded portion and the proximal threaded portion; 
 inserting the compression screw in the first bone portion and the second bone portion as a single unit until a distal end of the inner bone screw reaches a final location in the second bone and such that the cutting flute on the proximal threaded portion cuts the first bone as the proximal threaded portion becomes positioned within the first bone portion; 
 rotating the inserted outer sleeve to move the outer sleeve toward the inner bone screw while the distal end of the inner bone screw remains at the same final location such that the radially extending shoulder of the outer sleeve contacts an outer surface of the first bone and compresses the first bone towards the second bone, wherein the final location of the distal end of the inner bone screw remains the same before and after the compression. 
 
     
     
       2. The method of  claim 1 , further comprising rotating the outer sleeve to remove the inserted outer sleeve and inner bone screw without engaging any drive feature of the inner bone screw, wherein a proximal portion of the inner bone screw is deformed to prevent the outer sleeve from disengaging from the inner bone screw during the removal. 
     
     
       3. The method of  claim 2 , wherein the proximal end of the inner bone screw is swaged to prevent the outer sleeve from disengaging from the inner bone screw. 
     
     
       4. The method of  claim 1 , wherein the outer sleeve is positioned within the first bone portion and the inner bone screw is positioned within the first bone portion, the second bone portion, and across the gap. 
     
     
       5. The method of  claim 4 , wherein the distal threaded portion is positioned within the second bone portion, and the non-threaded portion is positioned across the gap. 
     
     
       6. The method of  claim 4 , wherein the non-threaded portion has a reduced diameter relative to the proximal threaded portion. 
     
     
       7. The method of  claim 4 , wherein the the distal threaded portion includes a cutting flute. 
     
     
       8. The method of  claim 1 , wherein the outer sleeve has a plurality of cutting flutes configured to cut into the first bone portion. 
     
     
       9. The method of  claim 1 , wherein the gap is a fracture. 
     
     
       10. A method for applying compression between a first bone portion and a second bone portion having a gap therebetween, the method comprising:
 providing a compression screw having an outer sleeve and an inner bone screw, the outer sleeve having a non-threaded head which defines a radially extending shoulder, the inner bone screw having a proximal threaded portion being threadedly engaged with the outer sleeve, wherein a distal end of the proximal threaded portion has at least one cutting flute configured to cut into the first bone portion as the inner bone screw is rotated, wherein a distal end of the proximal threaded portion has at least one cutting flute configured to cut into the first bone portion as the inner bone screw is rotated, and wherein the inner bone screw includes a distal threaded portion and a non-threaded portion between the distal threaded portion and the proximal threaded portion; 
 inserting the compression screw in the first bone portion and the second bone portion as a single unit until a distal end of the inner bone screw reaches a final location in the second bone and such that the cutting flute on the proximal threaded portion cuts the first bone as the proximal threaded portion becomes positioned within the first bone portion; 
 rotating the inserted outer sleeve to move the outer sleeve toward the inner bone screw while the distal end of the inner bone screw remains at the same final location such that the radially extending shoulder of the outer sleeve contacts an outer surface of the first bone and compresses the first bone towards the second bone, wherein the final location of the distal end of the inner bone screw remains the same before and after the compression; and 
 removing the compression screw by the outer sleeve without engaging any drive feature of the inner bone, wherein a proximal portion of the inner bone screw is deformed to prevent the outer sleeve from disengaging from the inner bone screw during the removal. 
 
     
     
       11. The method of  claim 10 , wherein the distal threaded portion is positioned within the second bone portion, and the non-threaded portion is positioned across the gap. 
     
     
       12. The method of  claim 10 , wherein the non-threaded portion has a reduced diameter relative to the proximal threaded portion. 
     
     
       13. The method of  claim 10 , wherein the distal threaded portion includes a cutting flute. 
     
     
       14. The method of  claim 10 , wherein the outer sleeve has a plurality of cutting flutes configured to cut into the first bone portion. 
     
     
       15. The method of  claim 10 , wherein the proximal portion of the inner bone screw is swaged to prevent the outer sleeve from disengaging from the inner bone screw.